G070517-00-0Charging Workshop - MIT - July071 T.J. Sumner – ICL lead and LIST Henrique Araujo,...
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Transcript of G070517-00-0Charging Workshop - MIT - July071 T.J. Sumner – ICL lead and LIST Henrique Araujo,...
G070517-00-0 Charging Workshop - MIT - July07
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T.J. Sumner – ICL lead and LIST
Henrique Araujo, Markus Schulte, Diana Shaul, Christian Trenkle (now Astrium), Simon Waschke, Peter Wass (now Trento)
Heritage (10 year mission)
Electrostatic Modelling
LTP EM Design
GEANT Modelling
Imperial College – LISA and LISAPFImperial College – LISA and LISAPFG070517-00-0
G070517-00-0 Charging Workshop - MIT - July07
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Charging of isolated proof-masses in satellite experiments
Effects of free charge• Lorentz force
• Electrostatic forces from mirror charges
• Spring Constants
• Forces from applied voltages
Charging Estimates• Rates
• Timelines
Charge Management• Measurement procedures
• Discharge procedures
G070517-00-0 Charging Workshop - MIT - July07
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Lorentz force noise
BvQFl HallEQ
Metallic Enclosure(Blaser)
BvQFl
222 vBQBQva nnn
G070517-00-0 Charging Workshop - MIT - July07
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Lorentz force noise
)Hz(10 C 104 HzT/ 105.2 4-13
11
ηQf
Bn
222 vBQBQva nnn
antinsignific term2 HzC/ 2
25.2 nd
f
QeQn
See later!
G070517-00-0 Charging Workshop - MIT - July07
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Electrostatic forces
n
i
iii
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CV
C
Q
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C
C
QV
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EF
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222 d
Ad
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spaceparameter - constrains 4
2 32
22
dTdd
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tQta d
2
32
2
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14
2
d
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A
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A
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Qa n
nn
2
332
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4
2d
d
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Cd
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Qk
G070517-00-0 Charging Workshop - MIT - July07
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Electrostatic forces
FE
k
C
kV
Q
C
C
k
Q
CV
C
kki
i ii
i
n
1
2 22
2
21
2
2
2
2
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222
nr
cmr
rn
rnn
kk
CV
mC
Q
k
CV
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C
mC
Q
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mC
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CV
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Qa
Common-mode voltage effects disappear to first order in force
Differential-mode voltages used for charge measurement – see later
2
2
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CV
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cmr
G070517-00-0 Charging Workshop - MIT - July07
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Summary of Charge LimitsEffect Limit (C)
Lorentz Noise 4x10-11 (10-4 Hz)
Displacement Noise 4x10-11
Charge Noise (d) 1.4x10-11 (10-4 Hz)
Stiffness (assymmetry) 3x10-12 (≡70mV)
Stiffness (Vdm) 10-8
Stiffness (1Vcm) 4x10-13
Potential (noise) 10-2
Potential (noise) (1Vcm) 3x10-11
Assumptions!!
d 10m
Vn 10 V/Hz
G070517-00-0 Charging Workshop - MIT - July07
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LISA Geant4 Geometry ModelS/C: LISA Solid Model (GSFC/NASA)
~200 placed volumes (85% total mass)
LTP IS: CAD (Carlo Gavazzi Space)
46 mm cube test mass, YZ injection
G070517-00-0 Charging Workshop - MIT - July07
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G070517-00-0 Charging Workshop - MIT - July07
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Charged Particle EnvironmentGalactic Cosmic Rays Solar Flare Events
G070517-00-0 Charging Workshop - MIT - July07
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Geant4 Physics Processes
Electromagnetics
•
Eth = 250 eV
Photo/Electronuclear
Hadronics
•
Intra-nuclear cascades
•
for protons and light ions
Decays
Particle Model Emin Emax
G4PreCompound 0 70 MeV
G4BinaryCascade 65 MeV 6.1 GeV p, n
G4QGSP 6 GeV 100 TeV
G4BinaryCascade 0 1.5 GeV
LEP 1.4 GeV 6.1 GeV +, -
G4QGSP 6 GeV 100 TeV
LEP 0 100 MeV d, t,
G4BinaryLightIonReaction 80 MeV 10 GeV/n 3He, GenericIon G4BinaryLightIonReaction 0 10 GeV/n
LEP 0 6.1 GeV K+, K-, K0L, K0S
G4QGSM 6 GeV 100 TeV
LEP 0 25 GeV p, n, , , -, -,
-, , +, +,
0, 0, -, - HEP 25 GeV 10 TeV
-, K- G4AbsorptionAtRest — —
p, n G4AnnihilationAtRest — —
n G4LCapture — —
n G4LFission — —
All hadrons G4LElastic 0 25 GeV
Hadronic ModelsMost G4 physics, including latest developments*
* Working within GEANT4 development team
G070517-00-0 Charging Workshop - MIT - July07
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G070517-00-0 Charging Workshop - MIT - July07
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Charging Multiplicity
Charge Spectrogram
LISAsolmin
Statistical Fluctuations
LISAsolmin
Q=Qi2~2.5 Q1
G070517-00-0 Charging Workshop - MIT - July07
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Charging SpectrumCharging Spectrum
LISAsolmin
Charging Spectra I
G070517-00-0 Charging Workshop - MIT - July07
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Spectral Charging Efficiency
p stoppingin test mass
Cascade/Stringchange-over
String ModelG4QGSP
Cascade ModelG4BinaryCascade
p stoppingbefore TM
G070517-00-0 Charging Workshop - MIT - July07
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primary solar GCR flux timeline
particle
activity , /s/cm2 , % N0 (x106
) CPU, days T, s N0/NQ
protons 4.29 92.0 121.1 150 200 2189
He-4 min 0.315 6.8 14.4 12 321 1002
He-3 0.0591 1.3 14.1 12168
3 1073
Total 4.66 100 149.6 174 − 419
protons 1.89 91.9 53.3 70 200 1889
He-4 max 0.142 6.9 9.3 11 462 849
He-3 0.0236 1.1 8.0 10240
2 928
Total 2.06 100 70.6 91 − 359
LISA Results
CERN LSF Cluster
2.2x108 Events
several CPU Years
200 s exposure time
Latest LISA result
– Astropart Phys. 22, 451-469 (2005)
Rate = +50 e/s
Noise = 30 e/s/Hz-1/2
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Non-Simulated PhysicsKinetic Electron
Emission
Potential Charging Processes:
Electron-induced kinetic emission Ion-induced kinetic emission
Atom sputtering (<0.01 at/s) X-ray transition radiation (<1 +e/s) X-ray Cherenkov radiation (<1
+e/s) Cosmogenic activation (<<1 +e/s) Hadron-induced x-ray emission
Kinetic emission of low energy secondary electrons (<50 eV) due to incident electrons (EIEE) and ions (IIEE) can be significant !
G070517-00-0 Charging Workshop - MIT - July07
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GP-B Simulations
Flare result is ~2-3 times too high but does not allow for spectral modification of proton flux at GP-B orbit
G070517-00-0 Charging Workshop - MIT - July07
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Shaul et al., 2004
Data Analysis and Clean-up
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Charging from Solar Events
Large solar flares (<1 /yr) can seriously disrupt normal operationMore modest flares (~1/yr) can deposit >109 charges in ~1 daySmall but frequent flares (>5 /yr) will contaminate the science dataRecommendation on specification of radiation monitor for LISAPF
SEP Event Distribution SEP Event Prediction
solar maximum
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Charging from Solar Flares ISmall SEP Event (GOES - May 20
2001)
Event fluence 6x105 p/cm2
Charging rate at peak flux ~160 +e/sTotal event charge ~3x106 +eFrequency 5-10 /year
Event fluence ~109 p/cm2
Charging rate at peak flux~130 000 +e/s
Total event charge ~5x109 +eFrequency << 1 /year
Large SEP Event (GOES - Sep 29 1989)
Need to characterise SEP distribution to lower fluences
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CR Variability – INTEGRAL and POLAR
No dramatic concern - some indications of isolated CR fluctuations, probably induced by solar events.
G070517-00-0 Charging Workshop - MIT - July07
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Radiation Monitor
ICL Detector concept: 2 PIN diodes in tetescopic configuration:
PINs have been kindly provided by GLAST collaboration
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Radiation Monitor
Coincidence spectrum for GCR Coincidence spectrum for SEP
G070517-00-0 Charging Workshop - MIT - July07
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Radiation Monitor
PIN Diode
PCB
Cu shielding
Radiation Monitor Geometry
GCR + SEP particle fluxes
Energy Spectrum
600s Energy Spectrum - entire simulation
Angular acceptance
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The CMS is a distributed system
Lamp assembly
UV Lamps and optics
Electronics
Fibre-optic cables
Inertial Sensor
ElectronicsInterface kit
Computer
Software
Spacecraft Electronics Modules Optical Bench
Procedures
Design Parameters
Subsystem Tests System Tests
CMS functions
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Inertial Sensor Design
•Electrode isolation•Capacitance matrix•Capacitance gradient•Cross-coupling matrix•Caging design•Charge sensitivity – electrode layout
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Charge Management SystemCharge Measurement using applied dither force in transverse direction with capacitive sensing of test-mass response.
Discharge technique using differential illumination of surfaces with UV illumination, with bias voltage enhancement if needed.
Cd
AQEFd
2
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Charge Measurement
Dither Technique•Different gaps in each direction give different measurement authority
•Need to see dither above residual drag-free position noise
•Assume transverse dither with 1nm/Hz position noise
2514
292/1 109.2
107.1
101dx
dxx w
wE
1.E+01
1.E+02
1.E+03
1.E+04
1.E+05
1.E+06
1.E-03 1.E-02 1.E-01
Dither Frequency (Hz)
Re
spo
nse
Tim
e (
s)
G070517-00-0 Charging Workshop - MIT - July07
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secondper ronsphotoelect 103
later) (see surfaces real''for measuring
needsbut target is A 2537at 10
4
o6
pe
Charge Neutralisation
tpevcvcflfi TTLTR
LTilfTfvc2Tvc ~ 3x1010 photons/s
Oxford Instruments HPSUV1000 fibre
Caburn FFTUV1000 (Special – remade in titanium with epoxy seal)
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•Dual Surface Illumination with dc bias voltage to modify ballistic trajectories
—2.1 V/m/eV gives Q/t ~ 15 charges/s
—80 V/m/eV gives Q/t ~ 6x103 charges/s
—500 V/m/eV gives Q/t ~ 3x104 charges/s
•Differential Surface Illumination using individual lamp currents to modify electron fluxes
—L() and L(I)
Charge Transport - t
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•Polar Ouput
Charge Transport
Polar Output of 1mm Diameter HPSUV Fibre Optic Cable
0
5
10
15
20
25
0 5 10 15 20 25
Polar Angle (Degrees)
Ou
tpu
t (P
ho
ton
s/s/
sr
[Re
lati
ve])
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•Differential Surface Illumination
Charge Transport
Electrode:Housing:TM
1 : 1.3 : 0.1
1 : 1.1 : 13.1
-3.9x103< <+3.5x103 /sQ
Add dc bias to drive harder when required
x5
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Charge Transport Test RigUV Lamp
G070517-00-0 Charging Workshop - MIT - July07
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Charge control with lamps
Electrode lamp off
TM lamp off, electrode lamp on
TM Lamp on
Rate ~ ±40000e/s
Simulator with physics in place for LTP
UV Lamp OFF
UV Lamp ON
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LISAPF Lamps• Derivative of those used on EINSTEIN and
ROSAT – 6,000 hr lifetimes
• Low pressure electric discharge cf rf discharge used on GPB.
• 8 housed in 3.5kg package for LISAPF
• 100:1 dynamic range using PWM at kHz frequencies
• 3W per lamp
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